75x Cluster of Solace → attempt at improving a crude umbral item into an umbral item.

150x Cluster of Solace → attempt at transforming an umbral item into a master umbral item.

In average, 2100 Clusters of Solace are spent on creating an umbral master item, according to Umbral Creation/Statistics. For more information about the process of creating, improving and transforming umbral weaponry, see Umbral Creation.

In Lower and Upper Roshamuul you can complete tasks for Inquisition gold, 100 of which can be exchanged for a Cluster of Solace at Sandomo in the Lower Roshamuul Inquisition base.